NOTE: These thoughts are probably a gross oversimplification and do not imply what motivates The Disney Co.
Let's look at this decision (playing devil's advocate) from a cost of business viewpoint. Yes, this is boring, but we own a business and I tend to think like a business person. Imagine you are in charge of overseeing VMK's role in Disney marketing. You've been crunching the numbers and reviewing expenses:
1. Costs involved in production of in-park vmk code cards = wages, benefits, and office expenses associated with a design/administrative team; and production and distribution of the cards.
2. Costs involved in operating an in-park VMK Central = all in (1.) above, PLUS building, maintenance, guest computers (plus maintenance), insurance, utilities, cast member expenses (wages, benefits, and training), design and production of quest materials/vmk code cards unique to each park, etc.
VMK'ers adjusted when the in-park VMK tours were cancelled. This decision to close VMK Central at Disneyland was probably motivated by expense cutting (I won't attempt explaining why Disneyland instead of WDW with a ten foot pole!). If they substitute something new, like more "free with purchase" in-park promotions, like more exciting additions coming in the next few months, we will again adjust.
I'm not agreeing with their decision -- just playing devil's advocate.